THE BQNES OF THE LOV/ER LIMB 



^^57 



part of the groove the upper surface gives origin to a portion of the 

 extensor brevis digitorum, and the fundiform ligament of Retzius, 

 When the astragalus is in position this groove is converted into a 

 short tunnel, called the sinus tarsi, which is occupied by the inter- 

 osseous ligament. The superior surface behind the articular portion 

 is rough, and supports a collection of fat. 



For Astragalus 



For Astragalus 



For Astragalus 



Interosseous Groove 

 Peroneal Spine 



_ Tubercle for Middle Fasciculus 

 of External Lateral Ligament 



,For Bursa 



For Tendo 



Achillis 



For Cuboid I i 



! 



Anterior Tubercle 



Internal Tuberck 

 Internal Surface 



Sustentaculum Tali, 

 with Groove below it for 

 Flexor Longus Hallucis 



Fig. 150. — The Right Os Calcis. 

 A, Superior View ; B, Internal View. 



The inferior surface is narrow and rough. Posteriorly it presents 

 two tubercles, the outer of which is small but prominent, whilst 

 the inner is large and blunt. The outer tubercle gives attach- 

 ment to the external division of the plantar fascia, and a 

 portion of the abductor minimi digiti, whilst the inner gives attach- 

 ment to the central and internal divisions of the plantar fascia, 



17 



